Question: Express your answer as a mixed number simplified to lowest terms. $20\dfrac{8}{20}-11\dfrac{4}{6} = {?}$
Solution: Simplify each fraction. $= {20\dfrac{2}{5}} - {11\dfrac{2}{3}}$ Find a common denominator for the fractions: $= {20\dfrac{6}{15}}-{11\dfrac{10}{15}}$ Convert ${20\dfrac{6}{15}}$ to ${19 + \dfrac{15}{15} + \dfrac{6}{15}}$ So the problem becomes: ${19\dfrac{21}{15}}-{11\dfrac{10}{15}}$ Separate the whole numbers from the fractional parts: $= {19} + {\dfrac{21}{15}} - {11} - {\dfrac{10}{15}}$ Bring the whole numbers together and the fractions together: $= {19} - {11} + {\dfrac{21}{15}} - {\dfrac{10}{15}}$ Subtract the whole numbers: $=8 + {\dfrac{21}{15}} - {\dfrac{10}{15}}$ Subtract the fractions: $= 8+\dfrac{11}{15}$ Combine the whole and fractional parts into a mixed number: $= 8\dfrac{11}{15}$